Such eccentric loom drive mechanisms are known and used primarily for the manufacture of simple fabric textures, for example, twill which is sensitive to stoppage marks.
When, due to breakage of the weft or warp thread the loom is stopped either automatically or by hand, some heald frames will stop in the upper shed position because of the type of binding. As a result, the respective warp threads will be stretched. This stretching can subsequently be seen as a defect in the finished fabric as a so-called "Stoppage mark".
So far, it is not known how to reliably avoid such a stoppage mark, except that within a relatively short time after the loom stops, the stretched warp threads are appropriately relieved of tension, which means that the respective heald frame or shaft must be moved toward a center shed position. This procedure up to now, can only be implemented in electronically controlled heald frame or shaft looms, wherein the heald frames or shafts are not moved by fixed associated cams, but rather are connected individually with the eccentric drive mechanism. When such fabrics, however, are made on conventional eccentric drive looms, it is not known how to avoid said stoppage marks.